The superior mechanical properties of polyoxymethylene (POM) molding compositions are the reason for their use in numerous applications. To improve their properties, the polyoxymethylene homo- and -copolymers are provided with additives to adapt the properties to the application, for example by using reinforcing fibers.
Combining reinforcing fibers with a polyoxymethylene polymer, for instance, can improve many physical properties of molded articles made from the polymer composition. For instance, fiber reinforced polyoxymethylene polymers have been shown to have excellent tensile strength, while having a good flex fatigue and creep performance.
A fiber reinforced polyoxymethylene composition, for instance, is disclosed in PCT Publication No. WO2012/049293, which is incorporated herein by reference. In the '293 application, a polyoxymethylene polymer is used that has a relatively high amount of hydroxyl groups. The polyoxymethylene polymer is combined with a coupling agent and at least one reinforcing fiber. The coupling agent is used to improve the compatibility between the polyoxymethylene polymer and the fibers. In the '293 application, a formaldehyde scavenger may optionally be included in the polymer composition for decreasing formaldehyde emissions.
The inventions disclosed in the '293 application have provided great advancements in the art. Compositions made according to the '293 application can have improved mechanical properties while also having low formaldehyde emissions.
The present disclosure is directed to further improvements in fiber reinforced polyoxymethylene polymer compositions and to improved products molded from the composition.